The invention concerns wireless communication systems with several antennas at a base station and one or more antennas at the receivers (Multiple Input Multiple Output System—MIMO). Use of several antennas makes it possible for the signals of different subscribers to be spatially distinguished during transmission or reception at the base station. Several subscribers can be served simultaneously by space division multiple access (SDMA) on this account, which significantly increases system throughput. At the same time, subscribers with several antennas can be supplied with more than one data stream as required (spatial multiplexing—SMux). For this purpose, the data streams can be sent, for example, in the strongest propagation directions of the transmission channel, the so-called spatial modes, so that they can be distinguished at the receiver. Different boundary conditions that lead to different mathematical SDMA transmission algorithms are conceivable. One boundary condition, for example, can be that the data streams sent to the individual subscribers should not interfere with each other.